Intaglio ink



30 fluoride.

Patented Mar. 22, 1927.

MATTHEW S. HOPKINS, OF READING, AND NORMAN UNDERWOOD, OF SWARTHMORE, PENNSYLVANIA, ASSIGNORS TO- CHARLES ENEU JOHNSON AND COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

INTAGLIO INK.

No Drawing.

rapidly fixed to the paper without danger of subsequent washing off. It is also desirable to avoid the use of inflammable, costly or otherwise objectionable ingredients.

These objects have been attained by us by in utilizing casein for thebasis of our compound. From casein may be formed a solution which serves as a good medium for the carriage or suspension of the coloring matter. The solution may be rendered stable I! against decomposition during storage, will respond to the requirements of rapid printing and the impressions can be quickly fixed on the paper with the usual methods. It is found that by combining with the casein solution, coloring matter in solid form which will melt during the drying step, the printing will adhere to the paper by the joint ,action of both color and casein without reliance on any other medium. In this way it 2 is feasible to eliminate the costly, inflammable and volatile oils, which are generally found necessary.

We prepare a solution of casein in water together with borax, ammonia and sodium While it is satisfactory to vary the proportions of the several ingredients it is found preferable and effective to use approximately 375 parts by weight of casein; 41 parts of borax; 45 parts of ammonia and 25 parts of sodium fluoride in 2040 parts of pure water. This solution in itself forms an adequate medium for-coloringmatter without the addition of further ingredients.

To this casein solution we add an appropriate amount of solid, finely ground color in the form of rosin, pitch, gilsonite (solid asphaltum), other gums, waxes or the like. Numerous color substances may be used but it is a desideratum that they be of a low 4 melting point, such that they will melt at the temperature to which the printed paper is ordinarily raised in the process of intaglio printing. The mixture may then be further ground or treated to make the ink so compounded uniform throughout and of proper working quality.

This compounded ink is found to be stable in that it does not suffer deterioration during under the usual printing conditions.

Application filed June 19, 1924. Serial No. 720,936.

storage either by decomposition or stratification (settling out of the color). It would appear that the ingredients in the casein solution react to form stable compounds in which the physical characteristics are peculiarly well adapted for ink purposes. In particular the casein is readily dissolved by the Water in the presence of the volatile ammonia and the borax. During the drying of the ink .on the printing surface, the volatilization of the ammonia causes a fixation of the casein which is not thereafter subject to removal by water alone.

In using this ink, for example in intaglio printing, the material is readily taken up by the engraved parts and transferred to the paper to make a notably clean impression. The casein solution binds the ink mass together against chipping or rubbing off. adheres readily to the paper and dries quiailfly ac to the volatilization of the ammonia, the casein and consequently the ink becomes substantially Waterproof. The solid color is uniformly held throughout the body of the ink even on that surface in adherence. with the paper.

As the temperature is raised these gums,

waxes, and the like melt and of themselves a solid coloring substance capable of acting as an agglutinant under the influence of a moderate heat.

2. An ink composed'of an aqueous solution of casein, borax, ammonia and sodium fluoride and containing a solid coloring substance capable of acting as an agglutina-nt under the influence of a. moderate heat.

In testimony whereof we have hereunto affixed our signatures.

MATTHEW S. HOPKINS. NORMAN UN DERWOOD. 

